Nickel cyclohexylamine complexes of 2,2-thiobis(p-alkylphenol),light stabilizers for polyolefins

ABSTRACT

Nickel cyclohexylamine complexes of 2,2&#39;&#39;-thiobis(p-alkylphenol) are new compounds, useful as ultraviolet light stabilizers and dye receptors for polyolefins.

United States Patent [191 Stretanski et al.

[451 Oct. 22, 1974 [75] inventors: Joseph Anthony Stretanski, Clinton; Joseph Adrian Hoffman, Somerville, both of NJ.

[73] Assignee: American Cyanamid Company,

Stamford, Conn.

[22] Filed: Oct. 23, 1973 [21] Appl. No.: 408,357

Related U.S. Application Data [62] Division of Ser. No. 240,764, April 3, 1972.

[52] U.S. Cl. t. 260/45.75 N, 8/178 R, 8/179, 8/180 [51] Int. Cl. C081 45/62 [58] Field of Search 260/4575 N, 439 R; 8/178 11,179,180

[56] References Cited UNITED STATES PATENTS 3,215,717 11/1965 Foster 260/4575 3,636,023 1/1972 Murray et al. 260/4575 3,692,738 9/1972 Mathis et al. .1 260/4575 Primary Examiner-V. P. Hoke Attorney, Agent, or Firm-Philip Mintz [5 7 1 ABSTRACT Nickel cyclohexylamine complexes of 2,2-thiobis(palkylphenol) are new compounds, useful as ultraviolet light stabilizers and dye receptors for polyolefins.

5 Claims, No Drawings NICKEL cvcLoHexy Ml COMPLEXES OF 2,2-THIOBIS (P-ALKYLPHENOL), ucnr STABILIZERS FOR POLYOLEFINS -'-N4 A Mine e wherein R is alkyl of l-l8 carbons, especially t-octyl. Illustrative of the amines disclosed as complexed to the nickel in the Foster patents are n-butylamine (Example 8), dodecylamine Example 3), ammonia (Example 1), and aniline (Example 4), although other amines are also disclosed therein.

Polyolefins are thermoplastic polymers and, as such, are normally heated to permit flow in molding processes, such as injection molding, extruding, blowmolding, and fiber spinning. Although the nickel amine complexes of the Foster patents are excellent for retarding the degradation of polyolefins by ultraviolet light, they are not as stable to heat as might be desired. Therefore, molded polyolefin compositions containing these nickel amine complexes of the Foster patents tend to be discolored due to partial degradation of the nickel amine complex itself on exposure to heat during molding of the polyolefin. This degradation is manifested by a distinct discoloration with time at processing temperatures progressing from pale yellow-green through brownish-green to black. This tendency to discolor on exposure to heat is related to the thermal stability of the nickel amine complex and is independent of processing antioxidants present in the compositions to protect the polyolefin. This is a definite drawback to the use of these complexes as ultraviolet light stabilizers for polyolefins.

When used to provide ultraviolet light stability in polyolefin fibers, these nickel amine complexes also serve as dye-sites for nickel-chelatable dyes used to color the fibers. While the nickel in these complexes is readily available to the chelatable dye, the tendency to discolor due to exposure to heat in forming such polyolefin fibers tends to interfere with the purity of the colors obtained.

In accordance with the present invention, it has been discovered that the corresponding complexes wherein the amine is cyclohexylamine are uniquely surprisingly resistant to such thermal degradation in polyolefin compositions while still retaining the excellent ability to stabilize such compositions against degradation by ultraviolet radiation. Thus, the nickel cyclohexylamine complexes of the present invention have the formula wherein R is alkyl of 1-l 8 carbons. The preferred compound of this invention is the one where R is t-octyl, having the formula t-octylQa\ Other nickel cyclohexylamine complexes within the scope of the present invention include those wherein R is butyl, hexyl, cyclohexyl, ethyl, nonyl, dodecyl, amyl, and octadecyl.

The nickel cyclohexylamine complexes of 2,2- thiobis p-alkylphenol) of the present invention can be prepared by the same process as the nickel amine complexes of the Foster patents using cyclohexylamine as the amine. Thus, the 1:1 aquo complex of the nickel complex of the 2,2'-thiobis(p-alkylphenol), prepared as in Example 2 of the Foster patents, and cyclohexylamine dissolved in a solvent, such as benzene or chloroform, is evaporated to dryness to produce the nickel cyclohexylamine complex of the 2,2-thiobis( palkylphenol). Alternatively, cyclohexylamine is added to a solution of the 2,2'-thiobis( p-alkylphenol) in chloroform and then an excess of an aqueous 20 percent solution of nickel acetate is added and the whole multiphase system is agitatedj After separation of the chloroform layer and evaporating to dryness, the nickel cyclohexylamine complex of the 2,2-thiobis( p-alkylphenol) remains as a dry residue. I

The nickel cyclohexylamine complexes of this invention can be used to stabilize and/or impart dye receptivity to a variety of polymers. Polyolefins, such as polyethylene and polypropylene are of primary importance although they can be used in polycarbonates and polyamides also. In such uses, the nickel cyclohexylamine complex is usually used at a concentration of 0.01 percent to about 5 percent by weight, preferably between 0.2 percent and 2 percent by weight, based on the polymer weight. Since the nickel cyclohexylamine complexes of this invention are surprizingly resistant to thermal degradation and discoloration, dyeings of fibers containing them are much truer in color as compared to the less thermally resistant nickel amine complexes of the Foster patents.

These new nickel cyclohexylamine complexes of 2,2-thiobis( p.-alkylphenol) of the present invention show superior properties as stabilizers in polymers,

such aspolyoletins, in various respects. They impart very little or no color to the composition; have good compatibility, so that fairly high concentrations can be employed without blooming; have relatively low volatility, so that the complex is retained in the composition Y are inserted into a Melt index Apparatus set at 290C.

nickel cyclohexylamine complexes. Any ultraviolet light absorber can be employed so long as it performs the functions generally required of an ultraviolet light absorber for polymers. These functions are well known to be high absorbency in the region of about 300-400 millimicrons, low absorbency in the region'above about 400 millimicrons, and solubility in and compatibility with polymers as well as stability towards light and heat. Examples of ultraviolet light absorberswhich can be used can be found in column 3,-lines 14-55 of Bright U.S. Pat. No.'3,636,0 22 and column 4, lines 1 -17 of Murray et al, US. Pat. No. 3,636,023. Y

When used in combination with such ultravioletlight absorbers, the nickel cyclohexylamine complexes of the present invention enhance the stability of the poly]- mer against degradation by ultraviolet radiation and substantially reduce the color of the polymeric compositions. In addition, these nickel cyclohexylamine complexes exhibit improved heat stability ,and color, both initially and after exposure to elevated temperatures as compared to the nickel amine complexes of the Foster patents. This is particularly important in polymer fibers since the combinations with the nickel amine complexes of the Foster patents have heretofore imparted a yellow coloration to the fibers causing problems with shade changes and dyeings. This difficulty is substantially eliminated by use of the nickel-cyclohexylamine complexes ofthisinvention. When used in combinations with such ultraviolet lightabsorbers, the combined content of these additives can be from about 0.05 percent to about percent on weight of polymer, and

preferably from 0.1 percent to .3'percent by weight.

' a numerical rating, each number above zero indicating a degree of discoloration:

0 no change 1 yellow-green 2 tan-green 3 slightly gray-tan 4 brown-green .5 gray-green 6 brown 7 gray 8 dark brown 9 black The effectiveness of the nickel cyclohexylamine complexes of this invention as light stabilizers can be determined by incorporating the compounds into the polymers by extrusion and pelletizing and then reextruding into monofilaments with a draw ratio of 7:1. The monofilaments can then be tested for retention of physical properties during Xenon weather-o-meter and Florida exposure.

The invention is further examples.

EXAMPLE I 't.butylphenol was added as a processing antioxidant.

The relative amounts of the nickel cyclohexylamine complex to the ultraviolet light absorber in the combination can range from 20:1 to 1:20.

The polymer compositions may also contain in addition to these nickel cyclohexylamine complexes and UV absorbers such other additives as may be needed or desired, for example, hindered phenol antioxidants such as 2, 6 -di-tert;butyl-p-cresol; 2,4,6-tr'i-tbutylphenol; 3,5-di-tert.butyl-4-hydroxyphenylpropioriic acid, octadecyl ester; and the like; secondary stabilizers such as distearylthiodipropionate; pigments; dyes; lubricants; and the like. 1 The effectiveness of the nickel complexes of this invention in polymers can be evaluated in a numberof ways. The *heat stability of the new complexes can be determined by dry blending with a polymer followed by milling. A milled sheet can then be cut into strips which The polypropylene and the nickel complexes were dry blended and milled on a standard plastic mill. The milled samples were cut into strips and inserted into a Melt Index Apparatus at 290C. and an extrudate removed every minute for 15 minutes in order to obtain a thermal discoloration profile for each composition, each extrudate being assigned a numerical color rating from 0-9 as described above.

TABLE I Color Rating of Polypropylene containing 1% Nickel Amine Complex of 2,2'-Thiobis p-t-octylghenol! Where Amine is As indicated Minutes Aging At 290C.

Amine 2 Cyclohexylarnine n-Butyiamine Z-Ethylhexylamine Dodecylamine Ammonia Aniline asses haw-came Ut eeoowmmo commotion E \DOIQNCU owooout The data in Tabel 1 illustrate the greatly improved thermal stabilityof the nickel cyclohexylamine complex of this invention compared with the nickel amine complexes of the Foster patents.

. EXAMPLE II illustrated by thefollowing ization. The pellets were re-extruded into monofilaments with a draw ratio of 7:1. The monofilaments were tested for retention of physical properties during Xenon Weatherometer and Floridaoutdoor exposure tests. The data are shown in Table II.

wherein R is alkyl of 1-18 carbons.

2. A composition as defined in claim 1 wherein R is t-octyl.

3. A polymeric composition as defined in claim 1 5 wherein said polymer of a mono-olefin is polyethylene The data demonstrate that the nickel cyclohexyl-' amine complex of this invention is as good as or slightly better than the nickel n-butylamine complex of the Foster patents as an ultraviolet light stabilizer.

We claim:

1. A polymeric composition of matter stabilized against deterioration by ultraviolet radiation comprising a polymer of a mono-olefin and from 0.1 to 5 percent of a complex having the formula RQ O j mm a MP Q or polypropylene and the nickel cyclohexylamine complex is present in a concentration of from 0.2 to l percent based on weight of polyolefin.

4. A polymeric composition as defined in claim 1 wherein said complex is the nickel cyclohexylamine complex of 2,2'-thiobis( p-t-octylphenol).

5. A polymeric composition as defined in claim 3 wherein said complex is the nickel cyclohexylamine complex of 2,2'-thiobis(p-t-octylphenol). 

1. A POLYMERIC COMPOSITION OF MATTER STABILIZED AGAINST DETERIORATION BY ULTRAVIOLET RADIATION COMPRISING A POLYMER OF A MONO-OLEFIN AND FROM 0.1 TO 5 PERCENT OF A COMPLEX HAVING THE FORMULA
 2. A composition as defined in claim 1 wherein R is t-octyl.
 3. A polymeric composition as defined in claim 1 wherein said polymer of a mono-olefin is polyethylene or polypropylene and the nickel cyclohexylamine complex is present in a concentration of from 0.2 to 1 percent based on weight of polyolefin.
 4. A polymeric composition as defined in claim 1 wherein said complex is the nickel cyclohexylamine complex of 2,2''-thiobis(p-t-octylphenol).
 5. A polymeric composition as defined in claim 3 wherein said complex is the nickel cyclohexylamine complex of 2,2''-thiobis(p-t-octylphenol). 